Question: Which is the business for which the chief executive officer is Warren Buffett?
Paraphrase: Which is the trade for which the chief official officer is Warren Buffett?
SPARQL (Wikidata):  select distinct ?sbj where { ?sbj wdt:P169 wd:Q47213 . ?sbj wdt:P31 wd:Q4830453 } 
Answer: Berkshire Hathaway